Rescue personnel work on a bus that overturned on Interstate 95 near Bowling Green, Va. in May of 2011. / Steve Helber, AP

by Bart Jansen, USA TODAY

by Bart Jansen, USA TODAY

The Transportation Department is moving faster to shut down bus companies because of safety violations in an effort to prevent crashes like the one last year in Virginia that killed four passengers.

Federal policy in place since 1990 allows a 45-day period for bus companies to prove they have fixed problems, which could be followed by a 10-day extension.

But the Federal Motor Carrier Safety Administration informally dropped extensions last year because the company Sky Express was operating under an extension when its fatal crash occurred May 31, 2011, in Doswell, Va.

Besides killing four people, the crash injured 49 others when the bus rolled onto its roof along northbound Interstate 95 on a trip from North Carolina to New York.

The agency proposed in the Federal Register on Monday banning any extensions permanently, which also applies to trucking companies hauling hazardous materials.

"There is no reason to allow motor carriers that we believe are unsafe to have additional time to operate during a safety review period," says Anne Ferro, head of the Federal Motor Carrier Safety Administration.

A rash of fatal bus accidents in recent years focused attention on the problem, including a crash in New York City in March 2011 killed 15 and injured 18 when the southbound bus fell on its side and had its top torn off.

More recently, a bus touring the Grand Canyon crashed Friday along Highway 93 in Arizona, with the driver dying and several passengers injured. On Oct. 8, a tour bus from Canada crashed in New Jersey and slid down an embankment, injuring 23.

The National Transportation Safety Board blamed the Virginia crash on the driver falling asleep after limited rest during the previous three days. Deborah Hersman, NTSB chairman, said in July after the board completed its investigation that the crash "never should have happened."

She noted that the Federal Motor Carrier Safety Administration could review only 2% to 3% of companies each year, but visited Sky Express repeatedly. The company, which has shut down, had no safety-management system, lax record keeping and no in-service training, according to NTSB.

The Transportation Department has highlighted safety measures against bus companies. In May, the department shut down 26 bus companies as "imminent hazards to public safety" that transported 1,800 passengers a day along Interstate 95 from New York to Florida.

The complaints focused on drivers without valid licenses, a lack of drug- and alcohol testing and a lack of safety inspections.

Roadside inspections doubled from 12.991 in 2005 to 25,703 in 2010, according to the department. The number of enforcement cases against unsafe passenger carriers grew from 36 in 2008 to 44 in 2010, the department says.